Thesis Thursday: Sophie Zimmermann

Embodied Relevance: Exploring the potential of existing concrete frame buildings (The case of the existing Christiaan Barnard Hospital)

© Sophie Zimmermann

Buildings have a large negative impact on the environment in terms of the natural resources and energy that they consume, as well as substantially contributing to global CO2 emissions. Two main sources within a building’s life cycle can be identified as the reasons behind this; namely the construction phase of a building and, the operational use of a building over its lifespan.

© Sophie Zimmermann

In the past, emphasis has been placed on the second, resulting in buildings being constructed to become increasingly energy efficient. The importance of carbon emission and energy usage is however slowly shifting from the operational emissions to the manufacturing of materials, transport and their eventual demolition and disposal (RICS, 2012). This embodied energy is wasted when buildings are demolished (with additional considerable energy and natural resources required to replace it), arguing for their refurbishment and continued use.

Mapping exercise of concrete frame buildings built before 1978 without a heritage grading. © Sophie Zimmermann

Rather than focusing on older well-built buildings, as well as current ones built according to environmental performance regulations, buildings built in a time in-between were sought after (which are also likely to be in use for many years to come, make up the majority of the existing built stock, amongst the least energy efficient buildings within our city, but also a current and future area of concern).

© Sophie Zimmermann

As a result, the dissertation focuses on the universal issue of 1960’s concrete frame buildings and investigates the potential for their continued re-use rather than demolition- with the aim to retain the existing embodied energy, while also focusing on adapting buildings to become more energy efficient.

In addition, these mundane buildings have the potential to be transformed, their meaning and impact on their surrounding altered, as well as the way in which they are regarded by the city and its inhabitants. Thus, the dissertation set out to combine two major challenges; environmental consciousness and the transformation and refurbishment of an already built environment.

© Sophie Zimmermann

The Christiaan Barnard Hospital was selected as the site for the design intervention, due to its uncertain future. The then current tenants have relocated to a custom designed hospital building, as the existing building no longer served its intended function sufficiently and would require extensive investment, addition and alteration to do so.

The building is an example of a generic office building – the ground floor is dominated by vehicle access, followed by seven floors of parking and a further seven floors above, originally designed as office space in 1969. These top seven floors have since 1984 been occupied by the hospital. The previous alterations to this robust building and structural system suggest that the building could and should be expected to change further for its usefulness and continued lifespan to be sustained.

© Sophie Zimmermann

The primary focus of the dissertation is to address and investigate the potential of retaining the existing concrete frame structure and creating a feasible design that adds environmental, yet also architectural and cultural value.

In the case of the Christiaan Barnard Hospital, this was done through retaining the bulk of the existing concrete frame (86%), while enhancing the internal quality of the building through the incorporation of light wells and various cuts and punctures throughout. While increasing occupancy well-being, this also allows for a comfortable interior climate through passive means and will improve the energy efficiency of the building, which is coupled with the energy savings from retaining the concrete frame.

Exposing and maintaining the concrete frame (largest component of embodied energy) and reincorporating the existing light wells into the design © Sophie Zimmermann

As a general approach the question; was asked what is worth keeping and what is worth changing? The various diagrams unpacks these restraints and opportunities which influenced the points of entry and the design process, showing them not as limitations but interesting challenges explored. Thus, the existing building is the design generator and not seen as an obstacle but rather a foundation for continued action.

Enlarging and enhancing these light wells through further punctures of the concrete frame. © Sophie Zimmermann

The light wells are combined with circulation and social spaces, which allows the naturally lit central public realm to function as the heart of the building. A masterplan for the building was developed around the existing light wells.

© Sophie Zimmermann
© Sophie Zimmermann
© Sophie Zimmermann

Through redirecting the vehicle movement, a portion of the parking is given over to an alternative use, namely residential. This results in an active street frontage on three sides of the building. The ground planes are given over to pedestrian movement and further public areas are at additional levels within the building. Various public and private uses were accommodated within the new design, yet are not a focal point of the dissertation as the space can be inhabited as needed within the city context.

© Sophie Zimmermann
© Sophie Zimmermann
© Sophie Zimmermann

EFTE cushions are used for a weather cover over the atrium space. These allow for maximum light transmission, and slightly raised, assist in achieving a naturally ventilated microclimate with the atrium. A lightweight modular steel frame structure with movable mesh screens was incorporated into the building’s façade to provide a fresh new look and allow for an interplay between the old and the new, while providing natural light, ventilation and shading.

© Sophie Zimmermann

The transformation communicates both the previous and continued life of the structure, the environmental benefits of the adaption and the positive architecture created for the inhabitants when incorporating the surround climate within the design.

© Sophie Zimmermann

The research and design explores and strives to serve as a precedent for a methodology for sustainable building refurbishment, as well as to encourage and showcase possible future uses and transformations of the valuable structural frame. The relatively large amounts of embodied energy in existing structures warrant greater recognition in a South African context, encouraging the re-use of existing structures.

© Sophie Zimmermann